Structure of Periodontium Flashcards
what is periodontium
tissues that supports tooth
What are the calcified connective tissues present in periodontium
Cementum
Alveolar bone
what are the non calcified tissues present in Periodontium?
Lamina propria
Perio. Ligament
what is cementum
covering the root of a tooth that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.
What is alveolar bone aka?
lamina dura
what is lamina propria
underlying connective tissues
What is line drawn at alveolar crest?
boundary between lamina propria and PDL
what do all 4 connective tissues have?
major matrix of type 1 collagen
what happens in Perio. disease?
periodontal tissue loss
alveolar bone degredation
what does mastication need?
occlusion and accuracy from wear of opp. teeth
What has periodontium evolved for ?
Shock absorber= protect enamel on crown
Allows continuous teeth eruption
What is lamina propria
fibrous connective tissue that insert into tooth and bone of alveolar crest
what do lamina propria fibres do?
hold attached gingiva to tooth
- attachment of gingiva to cuff= gingiva cuff
properties of junction epithelium?
non keratinised
stratitified squamous epitheliume
external/ internal basal lamina
upper surface= bond between gingiva and enamel
what do fibres below Junc. epithelium do ?
maintain strength of junction between tooth & gingiva
where does basal lamina deposit?
on enamel via hemi-desmosomes
what is free gingiva made of?
Oral epithelium
sulcular epithelium
Junction epithelium
connective tissue
What is cellular cementum
forms first and thin cover over whole root
what is accelular cementum
forms late and at root apex
What cells do cementum have?
Within= cementocytes
line surface= cementoblasts
what do cementoblasts do?
produce cementum matrix
what is matrix of cementum ?
HAP (found in bone/dentine/enamel)
intrinsic/extrinsic fibres- type 1 collagen
Cementum comp?
65%= inorganic 23%= organic 12%= water
What 3 forms of Cementoenamel junction ?
1) cementum overlaps= 70%
2) butt join= 20%
3) gap between , dentine exposed so inc. sensitivity and caries = 10%
what are incremental lines in cementum?
Lines of Salter
what’s between cementoblasts and mineralised cementum?
pale layer of unmineralised pre cementum
why does thickness of pre cementum constant?
matrix deposited on inner and periodontal surface at same rate
What fibres can insert into cementum from unmineralised PDL?
Sharpeys fibres where becomes mineralised in cementum
what was inserted fibre into cementum once called?
extrinsic fibres
what are extrinsic fibres formed?
Periodontal fibroblasts
what is mineralised matrix between extrinsic fibres?
Intrinsic cementum via cementoblasts
What cells are in the periodontium?
Fibroblasts
- cementoblasts
- osteoblasts
- osteoclasts
- epithelial cells
- macrophages
What is matrix in periodontium?
Collagen
ground substances
Glycoproteins/proteoglycans
oxylatin
What are small islands of epithelial celss?
cell rests of Malassez= remnant of development process of tooth root
What are principal fibres?
bundles of collagen fibrils
what is between collagen fibrils?
proteoglycans/glycoproteins
what are the 5 collagen fibre types?
Alveolar crest fibres Horizontal fibres Oblique Apical Inter-radicular
what are alv. crest firbes?
run from alveolar crest to inser into cementum
what are horizontal fibres?
bone to tooth
what are oblique fibres?
radiate from root apex
what are inter-radicular fibres?
multirooted tooth fibres run from inter radicular bone
- bone beneath roots
How are principle fibres formed?
tropocollagen> 5 membered microfibrils> classical fibrils> bundles> principle fibre bundles
What are oxytalan fibres ?
immature elastin fibres
what is the cellularity of periodontal ligament?
- many cell nuclei
- many fibroblasts= for connective tissues
What are fibroblast features?
high RER for protein production
- high turnover rate for collagen
how do periodontal ligament fibroblast degrade collagen?
phagocytic process
what are rests of malassez?
leftover of tooth development processes
what do PDL macrophages have?
microvilli
lysozymes
little RER or golgi
what is the periodontal blood supply?
from superior and inferior alveolar artery
what are the origin of capillaries in PDL?
Vessels in apex of tooth, intrabony spaces within alveolar
what do capillaries in PDL form?
arterioles in gingivae
what do capillaries/arterioles form?
plexus around socket wall
what are features of Periodontal capillaries?
fenestrations for efficient diffusion/filtration
What channels in socket wall called?
Volkmann’s canals- carry vessels between ligament & intrabony spaces so blood to ligament
